Fastening systems are widely known and widely used. Disposable absorbent articles are one example which is provided with fastening systems. The fastening systems provided on disposable absorbent articles are to form a closure of so-called open type absorbent articles (e.g., taped diaper) when in use or to adjust the dimension of the waist circumference of so-called pull-on type absorbent articles (e.g., pull-on diaper). In conventional arrangement of fastening systems on disposable diapers, the fastening member of the fastening system is provided to extend in the direction parallel to the lateral direction of the diaper such that the fastening member is pulled in the lateral direction for fastening the diaper and for forming a defined dimension of the waist opening. This provides a lateral tensioning force to keep the diaper in the abdominal region of the wearer.
Fastening members provided with stretchability have been also well known and used in absorbent articles such as diapers. The use of stretchable fastening member allows the diaper to accommodate wide ranges of wearer's waist circumference. However, the stress developed in the stretchable fastening member is very different depending on the circumference size of the wearer's waist. For example, the stretchable fastening member generates higher stress to cause excess forces on the wearer's body when the diaper having the stretchable fastening member is applied to a relatively big wearer than when the same diaper is applied to a relatively small wearer. Such excess forces cause skin problems such as red marking. In contrast, the stretchable fastening member generates only smaller stress to cause insufficient force on the wearer's body when the diaper is applied to a relatively small wearer than when the same diaper is applied to a relatively big wearer. Such insufficient force causes fitment problems of the diaper such as sagging. These problems are due to a typical behavior of the conventional stretchable fastening member in which stress developed in the stretchable fastening member simply continuously increases as strain of the stretchable fastening member increases.
European Patent publication EP 0 838 205 A3 published on May 31, 2002 discloses a disposable absorbent garment including a pair of differently stretchable ear members. Each differently stretchable ear member comprises a stretchable inner ear portion having a first stretchable characteristic and a stretchable outer ear portion having a second stretchable characteristic. It is stated that each stretchable outer ear portion preferably has a lower tension than stretchable inner ear portions, and each stretchable outer ear portion preferably has an elongation equal to or greater than that of a stretchable inner ear portion. Because stretchable inner ear portions are used primarily to fit and support absorbent article on the wearer, stretchable outer ear portions may have a lower tension so that they easily stretch to permit snap fastener to be closed without adding additional tension or stretch to inner ear portions that provide the proper fit and support. Thus, the stretchable inner ear portion and the stretchable outer ear portion may take a different stress-strain curve. However, the stress developed in such a stretchable ear member continuously increases as the strain of the stretchable ear member increases The stretchable ear member of the art can not reduce the stress developed in the stretchable ear member as it is stretched. Therefore, the stretchable ear member generates higher stress to cause excess forces on the wearer's body when the diaper is applied to a relatively big wearer. On the contrary, the stretchable ear member only generates stress to cause insufficient force on the wearer's body when the diaper is applied to a relatively small wearer. Thus, the stretchable ear member of the art limits the range of wearer's waist circumference size in which the diaper is comfortably applicable to the wearer.
Based on the foregoing, there is a need for an absorbent article having a stretchable fastening member being capable of controlling stress over the wide range of strain to accommodate wide ranges of wearer's waist circumference. None of the existing absorbent articles provides all of the advantages and benefits of the present invention.